package net.seninp.grammarviz.logic; import javax.swing.text.AttributeSet; import javax.swing.text.BadLocationException; import javax.swing.text.Document; import javax.swing.text.DocumentFilter; public class IntegerValueFilter extends DocumentFilter { @Override public void insertString(FilterBypass fb, int offset, String string, AttributeSet attr) throws BadLocationException { Document doc = fb.getDocument(); StringBuilder sb = new StringBuilder(); sb.append(doc.getText(0, doc.getLength())); sb.insert(offset, string); if (test(sb.toString())) { super.insertString(fb, offset, string, attr); } else { // warn the user and don't allow the insert } } private boolean test(String text) { try { Integer.parseInt(text); return true; } catch (NumberFormatException e) { return false; } } @Override public void replace(FilterBypass fb, int offset, int length, String text, AttributeSet attrs) throws BadLocationException { Document doc = fb.getDocument(); StringBuilder sb = new StringBuilder(); sb.append(doc.getText(0, doc.getLength())); sb.replace(offset, offset + length, text); if (test(sb.toString())) { super.replace(fb, offset, length, text, attrs); } else { // warn the user and don't allow the insert } } @Override public void remove(FilterBypass fb, int offset, int length) throws BadLocationException { Document doc = fb.getDocument(); StringBuilder sb = new StringBuilder(); sb.append(doc.getText(0, doc.getLength())); sb.delete(offset, offset + length); if (test(sb.toString())) { super.remove(fb, offset, length); } else { // warn the user and don't allow the insert } } }